Improvement in automatic air-valves for steam-cylinders



Patented m 16, 1876.

Fay. 3. J, y a

NZFETERS, PHOTO-LIYHOGRAPHER. WASHINGTON. D C.

UNITED STATES PATENT OFFICE.

NATHAN P. STEVENS, OE HOPK[NTON, ASSIGNOR TO HIMSELF AND JAMES N. LANDER, OF CONCORD, 'NEW HAMPSHIRE.

IMPROVEMENT IN AUTOMATIC AIR-VALVES FOR STEAM-CYLINDERS.

Specification forming part of Letters Patent No. 177,363, dated May 16, 1876; application filed March 10, 1876.

To all whom it may concern:

B'e it'known that I, NATHAN P. STEVENS, of Hopkinton, of the county of Merrimack, of the State of New Hampshire, have invented a new and useful Improvement in Steam-Engines; and do hereby declare the same to be fully described in the following specification and represented in the accompanying drawings, of which Figure 1 is a top view, Fig. 2 a longitudinal section, and Fig. 3 a transverse section, of a steamengine-cylinder valve and its seat provided with my invention, the purpose of which being to prevent what is termed vacuum obstruction of the'piston when the steam is shut off, and the piston in motion in the cylinder. Fig. 4 is an end elevation of the main or slide valve, and Fig. 5 is a front view of said valve and its seat-plate.

In carrying out my invention, I combine with the valveand its seat, provided with two ports and exhaust-cavities, as usual, an auxiliary valve and seat and lifting-spring, and also one or more passages, leading from said auxiliary valve-seat into the exhaust cavity or chamber of the valve, all being substantially as represented in the drawings, inwhich the main or slide valve is shown at A and its seat at B, the auxiliary valve at 0, its liftingspring at D, and the auxiliary-valve seat at E. The said valve-seat B has two ports, a b, leading out of it, and between them there is an exhaust-cavity, c. In the valve A there is also another exhaust cavity or chamber, d, out of the top of which one or more passages, 0, lead to and through the auxiliary-valve seat E, arranged in the top of the main valve A.

The auxiliary valve 0 is placed directly over the passage or passages e, and between two parallel and flanged guides or standards, G G, each of which is perforated transversely, as

shown at h h, to allow the steam to flow freely through it. The valve 0, at its middle, is fixed to the middle of a bow-spring, D, which, at its ends, is supported on the flanges f f of the guides G G. While the steam is let on or working the engine, the valve 0 will be closed; but as soon as the steam is shut off, its pressure being removed from the said valve 0, the spring D will raise such valve off its seat, whereby there will be opened a free communication between the valve-chest and the two ports, so as to enable the piston to work without vacuum obstruction.

The auxiliary valve is automatic in its operation.

In balanced valves, the auxiliary valve and lifter-spring should be applied to the chafe-plate or slides, which constitute the cover or top of the exhaust-cavity of the slidevalve.

What I claim as my invention or improvement in steam-engines is as follows-that is to say:

The valve A, provided with the perforated and flanged standards G G and the auxiliaryvalve seat E, in combination with the valve 0 and lifter-spring D, arranged between and applied to the said standards, all being substantially as specified.

NATHAN P. STEVENS.

Witnesses:

R. H. EDDY, J. R. Snow. 

